Synthesis and electrochemical properties of CuCo2O4@Co3O4 nanocomposite for supercapacitor application

Transition metal oxide–based pseudocapacitors with various valence states are of particular interest in the field of energy storage due to their increased specific capacitance values. In particular, Copper cobaltite nanomaterials have attracted more research focus due to their multiple oxidation states in comparison to other transition metals. Spinel structures of metal oxides are of tremendous interest for energy storage applications. Mixed valence metal cations in spinel cobaltites (MCo2O4) offer more electronic conductivity and electrochemical activity than single–component oxides. Natural abundance, good electrical and thermal stability, environment–friendly nature, and low cost motivates researchers for carrying out an extensive study of such materials. In this study, binary composite CuCo2O4@Co3O4 was synthesized by facile hydrothermal method. FT–IR, XRD, FEG–SEM and XPS studies have established the successful formation of all the nanocomposites were used to primarily characterize the sample. XRD showed the existence of all the synthesized materials in crystalline form. Cyclic voltammetry (CV), Galvanostatic Charge–Discharge (GCD) and Electrochemical Impedance (EIS) measurements were recorded to examine the electrochemical characteristics. The comparative specific capacitance of the synthesized CuCo2O4@Co3O4 nanocomposite displayed 542.77 Fg−1 using Glassy Carbon (GCE) as the working electrode whereas it exhibited 683.72 Fg−1 at the same current density of 1 Ag−1 using Nickel foam as the electrode substrate. The composite electrode exhibited an excellent pseudocapacitive behaviour using 1 M Na2SO4 and 1 M KOH as electrolytes respectively for electrochemical measurements. Impedance analysis reveals capacitive nature of the synthesized materials. Furthermore, cyclic stability for CuCo2O4@Co3O4 nanocomposite was found to be 76